Perfusion of a breeding liquid for breathing control and nutrition supply is essential for the breeding of life in processes such as cell culture, hydroponics and breeding. An apparatus for perfusing a liquid of small capacity is normally or usually such that water is moved by a water-flow pump to perfuse the liquid. For perfusion of a liquid of large capacity such as several hundred tons or several thousand tons, a super-huge water-flow pump is required in order to eliminate a stagnant area where the liquid is not perfused. Actually, a plurality of water-flow pumps are installed to cope with the stagnation, or the breeding liquid is completely replaced in order to cope with the stagnation. The present invention can cope with the automatic perfusion of the above-described liquid of small capacity only by simple aeration. It is considered that, in a principal aspect, the invention can cope with perfusion of a liquid of large capacity.